The present invention relates to novel compounds, to pharmaceutical compositions comprising the compounds, to processes for making the compounds and to the use of the compounds in therapy. More particularly, it relates to pyrrolidinyl urea and pyrrolidinyl thiourea compounds which exhibit TrkA kinase inhibition, and which are useful in the treatment of pain, cancer, inflammation, neurodegenerative diseases and certain infectious diseases.
The current treatment regimens for pain conditions utilize several classes of compounds. The opioids (such as morphine) have several drawbacks including emetic, constipatory and negative respiratory effects, as well as the potential for addictions. Non-steroidal anti-inflammatory analgesics (NSAIDs, such as COX-1 or COX-2 types) also have drawbacks including insufficient efficacy in treating severe pain. In addition, COX-1 inhibitors can cause ulcers of the mucosa. Accordingly, there is a continuing need for new and more effective treatments for the relief of pain, especially chronic pain.
Trk's are the high affinity receptor tyrosine kinases activated by a group of soluble growth factors called neurotrophins (NT). The Trk receptor family has three members: TrkA, TrkB and TrkC. Among the neurotrophins are (i) nerve growth factor (NGF) which activates TrkA, (ii) brain-derived neurotrophic factor (BDNF) and NT-4/5 which activate TrkB and (iii) NT3 which activates TrkC. Trk's are widely expressed in neuronal tissue and are implicated in the maintenance, signaling and survival of neuronal cells (Patapoutian, A. et al., Current Opinion in Neurobiology, 2001, 11, 272-280).
Inhibitors of the Trk/neurotrophin pathway have been demonstrated to be effective in numerous pre-clinical animal models of pain. For example, antagonistic NGF and TrkA antibodies such as RN-624 have been shown to be efficacious in inflammatory and neuropathic pain animal models (Woolf, C. J. et al. (1994) Neuroscience 62, 327-331; Zahn, P. K. et al. (2004)J. Pain 5, 157-163; McMahon, S. B. et al., (1995) Nat. Med. 1, 774-780; Ma, Q. P. and Woolf, C. J. (1997) NeuroReport 8, 807-810; Shelton, D. L. et al. (2005) Pain 116, 8-16; Delafoy, L. et al. (2003) Pain 105, 489-497; Lamb, K. et al. (2003) Neurogastroenterol. Motil. 15, 355-361; Jaggar, S. I. et al. (1999) Br. J. Anaesth. 83, 442-448) and neuropathic pain animal models (Ramer, M. S. and Bisby, M. A. (1999) Eur. J. Neurosci. 11, 837-846; Ro, L. S. et al. (1999); Herzberg, U. et al., Pain 79, 265-274 (1997) Neuroreport 8, 1613-1618; Theodosiou, M. et al. (1999) Pain 81, 245-255; Li, L. et al. (2003) Mol. Cell. Neurosci. 23, 232-250; Gwak, Y. S. et al. (2003) Neurosci. Lett. 336, 117-120).
It has also been shown that NGF secreted by tumor cells and tumor invading macrophages directly stimulates TrkA located on peripheral pain fibers. Using various tumor models in both mice and rats, it was demonstrated that neutralizing NGF with a monoclonal antibody inhibits cancer related pain to a degree similar or superior to the highest tolerated dose of morphine. Because TrkA kinase may serve as a mediator of NGF driven biological responses, inhibitors of TrkA and/or other Trk kinases may provide an effective treatment for chronic pain states.
Recent literature has also shown that overexpression, activation, amplification and/or mutation of Trk kinases are associated with many cancers including neuroblastoma (Brodeur, G. M., Nat. Rev. Cancer 2003, 3, 203-216), ovarian (Davidson. B., et al., Clin. Cancer Res. 2003, 9, 2248-2259), colorectal cancer (Bardelli, A., Science 2003, 300, 949), melanoma (Truzzi, F., et al., Dermato-Endocrinology 2008, 3 (1), pp. 32-36), head and neck cancer (Yilmaz, T., et al., Cancer Biology and Therapy 2010, 10 (6), pp. 644-653), gastric carcinoma (Du, J. et al., World Journal of Gastroenterology 2003, 9 (7), pp. 1431-1434), lung carcinoma (Ricci A., et al., American Journal of Respiratory Cell and Molecular Biology 25 (4), pp. 439-446), breast cancer (Jin, W., et al., Carcinogenesis 2010, 31 (11), pp. 1939-1947), Glioblastoma (Wadhwa, S., et al., Journal of Biosciences 2003, 28 (2), pp. 181-188), medulloblastoma (Gruber-Olipitz, M., et al., Journal of Proteome Research 2008, 7 (5), pp. 1932-1944), secratory breast cancer (Euthus, D. M., et al., Cancer Cell 2002, 2 (5), pp. 347-348), salivary gland cancer (Li, Y.-G., et al., Chinese Journal of Cancer Prevention and Treatment 2009, 16 (6), pp. 428-430), papillary thyroid carcinoma (Greco, A., et al., Molecular and Cellular Endocrinology 2010, 321 (1), pp. 44-49) and adult myeloid leukemia (Eguchi, M., et al., Blood 1999, 93 (4), pp. 1355-1363). In preclinical models of cancer, non-selective small molecule inhibitors of Trk A, B and C were efficacious in both inhibiting tumor growth and stopping tumor metastasis (Nakagawara, A. (2001) Cancer Letters 169:107-114; Meyer, J. et al. (2007) Leukemia, 1-10; Pierottia, M. A. and Greco A., (2006) Cancer Letters 232:90-98; Eric Adriaenssens, E., et al. Cancer Res (2008) 68:(2) 346-351).
In addition, inhibition of the neurotrophin/Trk pathway has been shown to be effective in treatment of pre-clinical models of inflammatory diseases with NGF antibodies or non-selective small molecule inhibitors of Trk A. For example, inhibition of the neurotrophin/Trk pathway has been implicated in preclinical models of inflammatory lung diseases including asthma (Freund-Michel, V; Frossard, N., Pharmacology & Therapeutics (2008) 117(1), 52-76), interstitial cystitis (Hu Vivian Y; et. al. The Journal of Urology (2005), 173(3), 1016-21), inflammatory bowel diseases including ulcerative colitis and Crohn's disease (Di Mola, F. F, et. al., Gut (2000) 46(5), 670-678) and inflammatory skin diseases such as atopic dermatitis (Dou, Y.-C., et. al. Archives of Dermatological Research (2006) 298(1), 31-37), eczema and psoriasis (Raychaudhuri, S. P., et al., J. Investigative Dermatology (2004) 122(3), 812-819).
The TrkA receptor is also thought to be critical to the disease process in the infection of the parasitic infection of Trypanosoma cruzi (Chagas disease) in human hosts (de Melo-Jorge, M. et al., Cell Host & Microbe (2007) 1(4), 251-261).
Trk inhibitors may also find use in treating disease related to an imbalance of the regulation of bone remodeling, such as osteoporosis, rheumatoid arthritis, and bone metastases. Bone metastases are a frequent complication of cancer, occurring in up to 70 percent of patients with advanced breast or prostate cancer and in approximately 15 to 30 percent of patients with carcinoma of the lung, colon, stomach, bladder, uterus, rectum, thyroid, or kidney. Osteolytic metastases can cause severe pain, pathologic fractures, life-threatening hypercalcemia, spinal cord compression, and other nerve-compression syndromes. For these reasons, bone metastasis is a serious and costly complication of cancer. Therefore, agents that can induce apoptosis of proliferating osteoblasts would be highly advantageous. Expression of TrkA receptors has been observed in the bone forming area in mouse models of bone fracture (K. Asaumi, et al., Bone (2000) 26(6) 625-633). In addition, localization of NGF was observed in almost all bone forming cells (K. Asaumi, et al.). Recently, it was demonstrated that a Trk inhibitor inhibits the tyrosine signaling activated by neurotrophins binding to all three of the Trk receptors in human hFOB osteoblasts (J. Pinski, et al., (2002) 62, 986-989). These data support the rationale for the use of Trk inhibitors for the treatment of bone remodeling diseases, such as bone metastases in cancer patients.
Several classes of small molecule inhibitors of Trk kinases said to be useful for treating pain or cancer are known (Expert Opin. Ther. Patents (2009) 19(3), 305-319).